fix: gstack-skill-end releases its run on the workflow lease, so a finished /ship stops blocking gstack-upgrade (GST-1205)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

docs/capy-install.md

@@ -187,7 +187,7 @@ run from inside a workflow (/ship's docs step running `install.sh --for
 document-release`, #3571) prints `SELF_UPGRADE: skipped (a gstack run in this
 session holds a workflow lease on this installation: ... (UPGRADE_BUSY))`,
 leaves the checkout where the run started and stays ok with `behind=`. Each
-`gstack-skill-start` renews the lease. On Capy the leased pid is the machine's
+`gstack-skill-start` renews the lease and records its `SESSION_ID` as an open run; `gstack-skill-end` closes that run, and a lease whose runs are all closed is idle and blocks nothing, so a finished /ship no longer holds the upgrade back (GST-1205). A lease with no recorded run (written without `--run`, or by an older gstack) counts as before. On Capy the leased pid is the machine's
 long-lived `capy-server`, so the deferral ends when the lease turns 120
 minutes old, not when the process exits. Every session on the machine runs
 under that same `capy-server`, so `bin/gstack-upgrade` run by hand also
@@ -231,7 +231,7 @@ identities, a taker stalled over 2 minutes between its `mkdir` and its owner
 rename can be broken and then publish into its successor's lock. While a live process
 holds the lock, or it cannot be taken at all, `touch` exits 3 without writing
 (`gstack-skill-start` reports that the session holds no lease) and a reclaim
-keeps the lease. `bin/gstack-lease list` shows `alive|dead|stale`, and
+keeps the lease. `bin/gstack-lease list` shows `alive|idle|dead|stale`, and
 `GSTACK_UPGRADE_FORCE=1` overrides.
 
 ## What the installer does

docs/troubleshooting.md

@@ -1705,10 +1705,12 @@ session holds a workflow lease on this installation: pid <p> (<age>m
 <checkout>/bin/gstack-upgrade once the lease is 120 minutes old, or
 GSTACK_UPGRADE_FORCE=1 <checkout>/bin/gstack-upgrade when no other session uses
 this checkout (UPGRADE_BUSY))` and leaves the
-checkout where the run started. Each `gstack-skill-start` renews the lease.
+checkout where the run started. Each `gstack-skill-start` renews the lease
+and opens a run that its `gstack-skill-end` closes; a lease whose runs are all
+closed is idle and never counts (GST-1205).
 
 **Fix.** Wait for those sessions to finish (`bin/gstack-lease list` shows
-every lease with its age and `alive|dead|stale`; a holder is named as
+every lease with its age and `alive|idle|dead|stale`; a holder is named as
 `pid <p> (<age>m <command>)`), then re-run `bin/gstack-upgrade`. For the
 session's own run, or a shared-harness lease, re-run once the lease is 120
 minutes old. When you know no other session uses the checkout, `GSTACK_UPGRADE_FORCE=1 bin/gstack-upgrade`